A team of researchers from the Colorado School of Public Health led by Dr. Lisa McKenzie looked at cases of a specific type of bone marrow cancer known as acute lymphocytic leukemia as well as cases of non-Hodgkin lymphoma. They weighed the number of cases reported in regions of high-density and low-density oil and gas operations against the reported cases of other kinds of cancer.
Their study Childhood hematologic cancer and residential proximity to oil and gas development shows children and young adults between the ages of 5 and 24 with acute lymphocytic leukemia were 4.3 times more likely to live in the densest area of active oil and gas wells than those with other cancers. No link was found between non-Hodgkin lymphoma and oil and gas development.
According to the report, U.S. oil and gas development has grown rapidly over the past 15 years. In Colorado, oil and gas development within communities and residential areas is currently on the rise, impacting the health of hundreds of thousands of residents. People living on the Front Range are constantly exposed to air pollution that violates current air quality standards. Oil and gas operations continuously emit known carcinogens into our air and water. Benzene is the chief chemical component in the BTEX chain (benzene, toluene, ethylbenzene, xylene) of oil and gas emissions. A Chinese study released in 2004 revealed there is no safe exposure level for benzene.
“Over 378,000 Coloradans and millions of Americans currently live within a mile of at least one oil and gas well, and petroleum development continues to expand into residential areas,” said lead investigator Dr. Lisa McKenzie, assistant research professor at the Colorado School of Public Health. “The findings from our registry-based case control study indicate that young Coloradans diagnosed with one type of childhood leukemia are more likely to live in the densest areas of oil and gas sites. More comprehensive research that can address our study’s limitations is needed to understand and explain these results.”
According to current research, over 15 million Americans now live within 1.6 kilometers (1 mile) of oil and gas development. There are hundreds of oil and gas wells within one mile of a home in Colorado’s most intensive areas of oil and gas development. The study indicates that people living in areas of oil and gas development may be at an increased risk for health effects, including cancers, resultant from such industrial exposures.
Data for the study was obtained from the Colorado Central Cancer Registry and the Colorado Oil and Gas Information System. The study included 743 young Coloradans aged 0-24 years living in rural Colorado and diagnosed with cancer between 2001 and 2013.
Researchers used information from the Colorado Oil and Gas Information System to build a geocoded dataset with coordinates of all oil and gas wells in rural Colorado and determined dates for when each well was active.
Geocoded residential addresses of cancer patients at the time of diagnosis were linked to active well locations in the year of diagnosis and active well locations in each of the 10 years preceding the cancer diagnosis. They then took the inverse of each distance and summed the inverse distances to calculate inverse distance weighted oil and gas well counts within a 16.1 km radius of each participant’s residence at cancer diagnosis for each of the 10 years prior to the date of the cancer diagnosis. The inverse distance weighted well count method gives greater weight to the wells nearer the home. Age, race, gender, income, elevation of residence and year of cancer diagnosis all were considered in the analysis.
Reaction to the study from the state and the industry was swift, indicating that perhaps the specificity of these findings has rattled their cages.
The Colorado Oil and Gas Association (COGA) issued this terse statement:
This is a very serious allegation. If you recall, Lisa McKenzie’s last major study in 2014 was disavowed by state health officials and in fact the state’s top health official went so far as to say the public could be “misled” by it. University researchers shouldn’t be in the game of scaring people just to secure additional funding. Still, public health is obviously of great concern to our industry and we will review her data immediately. We also look forward to the state’s review of the study.
Apparently the only ones scared of this report are the industry and the CDPHE.
Cathy Proctor at the Denver Business Journal generously turned over to her column to Dr. Larry Wolk, executive director for the Colorado Department of Public Health and Environment (CDPHE), so he could vent a lengthy barrage critical of the data sans interruptions or opposing arguments.
Among other things, Wolk said this:
“Based on this study and other studies/data/information we have to date, we find no increased risk for childhood leukemia, especially when considering the current setbacks [of a minimum 500-foot buffer between oil and gas wells and homes],” Wolk said in an email to the DBJ.
Parse that to mean the CDPHE hasn’t isolated specific types of leukemia from other types of leukemia, which is what McKenzie’s study actually did. Wolk is probably referring to all types of leukemia. The study shows no increase in non-Hogkins lymphoma near oil & gas operations therefore that would skew the CDPHE figures which include all types of leukemia.
Looking over the statewide database of child cancer patients, we “see no increases in leukemia in oil and gas developed counties vs those that don’t and vs the statewide expected average,” Wolk said.
Okay. I re-read that 10 times and it still doesn’t make any sense. The study is based on proximity to oil & gas operations, not the county in which the cases are reported.
However by the authors’ own admission, the study was limited by the low occurrence of leukemia and non-Hodgkin lymphoma in rural Colorado, lack of specific age at cancer diagnosis and the fact that all study participants had been diagnosed with cancer. The study was also limited by the lack of information on specific activities at the well sites, place of residence before cancer diagnosis, other sources of pollution around the residence and individual characteristics such as common infections and family history of cancer.
Wolk also said:
During the last six years, the CDPHE has looked at 100,000 air quality samples from areas surrounding oil and gas development, including looking for benzene.
The results of those tests, “indicate that benzene exposures are within the [U.S. Environmental Protection Agency’s] generally acceptable cancer risk range and are similar to those of Denver,” Wolk’s statement said.
Earthworks FLIR videos of 65 oil & gas facilities across Colorado challenge those results. But the study isn’t about whether or not there is benzene in our air or at what levels. The study reveals that a specific type of leukemia associated with prolonged exposure to benzene has shown up in young humans living near oil & gas operations.
The study concludes that future research should incorporate information on oil and gas development activities and production levels, as well as levels of specific pollutants of interest like benzene, near homes, schools and day care centers. It recommends such research consider specific ages and residential histories, compare cases to controls without cancer and address other potential confounders and environmental stressors.
Wolk told the Denver Post the issue is important to explore further, adding that CDPHE hopes to publish a summary of research on the health impacts of oil and gas development in the coming weeks. Note, he said “hopes.”
The other study authors are William Allshouse, Tim Byers, Berrin Serdar and John Adgate of the Colorado School of Public Health at CU Anschutz and Edward Bedrick of the College of Public Health at the University of Arizona.